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              <h1>Kafka的高吞吐与可靠性 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
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      <script>
        const quizData = [
  {
    "question": "为了在Kafka生产者端实现最高级别的消息可靠性，防止消息丢失，应该如何配置`acks`参数，其作用是什么？",
    "options": [
      "acks=0，生产者发送消息后不等待任何确认，吞吐量最高。",
      "acks=all，确保消息不仅被Leader副本写入，还被所有ISR（同步副本集）中的副本成功写入后，才返回确认。",
      "acks=1，仅等待Leader副本成功写入消息后即返回确认，这是性能和可靠性的折中。",
      "acks=-1，这是一个与`acks=all`等效的别名，用于保证最高可靠性。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "配置`acks=all`（或-1）提供了最高的消息持久性保证。它要求分区的Leader副本必须等待所有处于同步状态（ISR）的Follower副本都确认收到消息后，才向生产者发送ACK。这可以有效防止在Leader节点故障时发生数据丢失。",
    "source": "文档中「二、优化 Kafka 的可靠性」-「1. 生产者端可靠性优化」-「ACK 机制」部分",
    "hint": "文档中提到，为了“最大程度保证消息的可靠性”，需要确保所有同步副本集都成功写入。"
  },
  {
    "question": "在优化Kafka生产者的吞吐量时，哪两个参数组合最适合用来实现消息的批量发送，以减少网络请求次数？",
    "options": [
      "`batch.size` 和 `linger.ms`",
      "`compression.type` 和 `retries`",
      "`fetch.min.bytes` 和 `fetch.max.wait.ms`",
      "`message.max.bytes` 和 `replica.fetch.max.bytes`"
    ],
    "correctAnswerIndex": 0,
    "explanation": "`batch.size`定义了一个批次可以发送的消息大小上限（字节）。`linger.ms`则让生产者在发送前等待指定的时间（毫秒），以便收集更多的消息组成一个更大的批次。这两个参数结合使用，可以有效地将多条消息打包发送，从而显著提高吞吐量。",
    "source": "文档中「一、优化 Kafka 的高吞吐量」-「1. 生产者端优化」-「批量发送」部分",
    "hint": "寻找与生产者端“打包成一个批次发送”直接相关的两个配置参数。"
  },
  {
    "question": "为了防止消费者在处理完消息后、提交偏移量前发生故障而导致消息重复消费或丢失，文档推荐的最佳实践是什么？",
    "options": [
      "启用死信队列（Dead Letter Queue）来存储所有消息。",
      "将`enable.auto.commit`设置为`true`并缩短提交间隔。",
      "将`enable.auto.commit`设置为`false`，并在业务逻辑成功处理消息后进行手动提交。",
      "增加消费者组内的消费者实例数量。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "关闭自动提交偏移量（`enable.auto.commit=false`）并将控制权交给应用程序是保证“至少一次”消费语义的关键。通过在消息被完全处理后手动调用提交API，可以确保即使消费者进程崩溃，偏移量也不会被错误地提前更新，从而防止数据丢失或重复处理。",
    "source": "文档中「二、优化 Kafka 的可靠性」-「3. 消费者端可靠性优化」-「偏移量管理」部分",
    "hint": "为了确保消费的幂等性，文档建议关闭自动提交并采取手动控制的方式。"
  },
  {
    "question": "在Kafka Broker端，哪个关键配置项可以防止因Leader副本崩溃后，一个数据落后的副本被选举为新的Leader而导致的数据丢失风险？",
    "options": [
      "将`replication.factor`设置为1",
      "将`unclean.leader.election`设置为`false`",
      "增大`log.segment.bytes`的值",
      "将`min.insync.replicas`设置为1"
    ],
    "correctAnswerIndex": 1,
    "explanation": "将`unclean.leader.election`设置为`false`是一项重要的可靠性配置。它禁止了非同步副本（即数据可能落后的副本）在原Leader失效时被选举为新的Leader。这保证了只有拥有最新数据的ISR副本才能成为Leader，从而避免了数据丢失。",
    "source": "文档中「二、优化 Kafka 的可靠性」-「2. Broker 端可靠性优化」-「数据持久化」部分",
    "hint": "在“数据持久化”一节中，有一个配置项专门用于避免“非同步副本”被选为Leader。"
  },
  {
    "question": "当Kafka生产者的重试机制(`retries` > 0)被激活时，可能会导致同一条消息被发送多次。应该启用哪个特性来保证消息在Broker端只被写入一次，从而避免数据重复？",
    "options": [
      "启用消息压缩 `compression.type`",
      "启用幂等性 `enable.idempotence=true`",
      "使用轮询分区策略（Round-Robin）",
      "配置 `acks=1`"
    ],
    "correctAnswerIndex": 1,
    "explanation": "生产者幂等性（`enable.idempotence=true`）是Kafka为解决消息重复问题提供的核心功能。启用后，生产者会为每条消息分配一个唯一的序列号，Broker会根据这个序列号来判断消息是否重复，从而确保即使在重试的情况下，消息也只会被持久化一次。",
    "source": "文档中「二、优化 Kafka 的可靠性」-「1. 生产者端可靠性优化」-「幂等性」部分",
    "hint": "文档中明确提到了一个设置，用于“确保生产者在重试时不会因重复写入导致消息重复”。"
  },
  {
    "question": "根据文档，优化Kafka消费者吞吐量的最直接方法是利用其并行处理能力。以下哪种做法最能有效实现这一点？",
    "options": [
      "将消费者组内实例数设置为远大于分区数。",
      "增加`fetch.max.wait.ms`的值来减少网络延迟。",
      "将消费者组内的消费者实例数与Topic的分区数相匹配。",
      "关闭消费者的批量拉取功能。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Kafka的并行消费模型是基于分区的。一个消费者组内，一个分区最多只能被一个消费者实例消费。因此，为了完全利用分区的并行能力，理想状态是让消费者实例的数量等于或小于分区的数量。当两者相等时，每个消费者负责一个分区，并行度达到最大化。",
    "source": "文档中「一、优化 Kafka 的高吞吐量」-「3. 消费者端优化」-「并发消费」部分",
    "hint": "思考一下消费者实例和分区之间的一对一关系如何最大化并行能力。"
  },
  {
    "question": "文档在“吞吐量与可靠性之间的权衡”部分指出了一个核心矛盾。以下哪个选项最准确地描述了这种权衡关系？",
    "options": [
      "使用消息压缩可以同时提升吞吐量和可靠性，没有权衡。",
      "增加副本数量（`replication.factor`）会降低吞吐量，但对可靠性没有影响。",
      "手动提交消费者偏移量能确保可靠性，但会显著降低消费效率。",
      "生产者设置`acks=1`可以获得更高的吞吐量，但牺牲了部分数据可靠性；而`acks=all`则相反。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "这是一个经典的权衡：当生产者设置`acks=1`时，只需Leader确认即可，等待时间短，网络往返少，因此吞吐量高，但如果Leader在同步给Follower前宕机，数据会丢失。而`acks=all`需要等待所有ISR副本确认，延迟更高，吞吐量较低，但可靠性得到了最大保障。",
    "source": "文档中「三、吞吐量与可靠性之间的权衡」-「1. 生产吞吐与可靠性权衡」部分",
    "hint": "在文档的最后部分，对比了`acks=1`和`acks=all`对性能和可靠性的不同影响。"
  }
];
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                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  